Desolate Neighbors

You can forget about sending a welcome basket to any neighbors on the planets orbiting Barnard’s Star, the second-closest star system to Earth. Conditions on all four of its planets are likely to be hostile to life. Barnard’s Star is just six light-years away – only the triple-star system Alpha Centauri is closer. The star is much smaller and lighter than the Sun. And at visible wavelengths, it’s less than one-thousandth as bright as the Sun. In 2024, four planets were discovered orbiting the star. None of them is more than about four million miles out – about four percent the distance from Earth to the Sun. All of them probably are locked so that one hemisphere always faces the star, just as one hemisphere of the Moon always faces Earth. And they orbit in such a way that the system has remained stable over the star’s 10-billion-year lifetime. A recent study provided new details on all four planets. All of them are less massive than Earth and Venus, but heavier than Mars. The combination of their masses and the composition of Barnard’s Star itself suggests they’re dense and rocky, like Earth. They’re probably quite dry, and none of them is likely to have an atmosphere. That makes them unlikely places to find neighbors. Barnard’s Star is well up in the west-southwest at nightfall. It’s not far from the brightest star of Ophiuchus. But it’s so faint that you need a telescope to pick it out.   Script by Damond Benningfield